The pointer indicated the point at which water is moving rapidly out of the paramecium as the contractile vacuole contracts.
- The pointer specifically indicates where the water solute concentration dropped. In order for the solute concentration of the water to drop, more water would have to be added.
- This means that water from the paramecium moves into the surrounding water as the contractile vacuole contracts. Consequently, the solute concentration of the surrounding solution decreases.
- When water moves from the solution into the paramecium, the solute concentration increases and this forms a continuous cycle in the graph.
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